1. Field of the Invention
The present invention relates to an ink ejecting device and a method for manufacturing the ink ejecting device.
2. Description of Related Art
Among nonimpact type printers, which have expanded the market in part by obsoleting existing impact type printers, an ink jet printer is simplest in principle and easily realizes color printing in multiple gradation. Particularly, the use of drop-on-demand type printers, which eject ink droplets for printing, is rapidly spreading because of their excellent efficiency of ejection and lower operation cost.
A typical drop-on-demand type printer includes a Kyser type disclosed in U.S. Pat. No. 3,946,398 and a thermal jet type disclosed in U.S. Pat. No. 4,723,129. However, those conventional printers have difficult problems. The Kyser type printer is difficult to miniaturize, while the thermal jet type printer requires higher heat-proof characteristics of ink because intense heat is applied thereto.
To simultaneously overcome the above-mentioned defects, U.S. Pat. No. 4,879,568 has disclosed, as a novel system, a shear mode type printer.
The shear mode type printer introduces an ink driving method in which an electrode to which a voltage is applied is placed in contact with ink. Therefore, the shear mode type printer has always been accompanied by a disadvantage because an electrode must be covered with an insulating layer, resulting in increased cost and decreased productivity.
However, in recent years, a shear mode type printer having an ink driving method not utilizing an insulating layer has been proposed as a result of improvement in the shear mode type driving method.
For example, in the ink jet printer described in U.S. Pat. No. 4,879,568, an air chamber provided between ink channels is formed to have a narrower width than the ink channels to achieve higher integration of ink channels and printing resolution.
However, the above-mentioned prior art devices suffer from disadvantages since voltage is applied directly to the electrodes of the ink emitting chambers.
The present invention has been proposed to overcome the problems described above and it is therefore an object of the present invention to provide an ink ejecting device that can accurately remove electrodes at the bottom parts of grooves with lower cost and higher productivity. Another object is to provide a method of manufacturing an ink ejecting device.
According to a first aspect of the present invention, to achieve the object explained above, an ink ejecting device comprises a plurality of eject channels for ejecting ink, a plurality of non-eject channels provided in both sides of the eject channels that do not eject ink, separation walls at least partly formed of polarized piezoelectric ceramic to isolate the eject channels from the non-eject channels, and electrodes formed on the separation walls to generate an ink driving field at the piezoelectric ceramic with application of a voltage thereto, with the electrodes in the non-eject channels being divided such that the non-eject channels are wider than the eject channels.
According to a second aspect of the present invention, the ink ejecting device does not require any insulating film on the electrodes within the eject channels that are in contact with ink, by grounding the electrodes in the eject channels and applying a voltage to the electrodes in the non-eject channels.
According to a third aspect of the present invention, there is provided a method of manufacturing an ink ejecting device comprising a plurality of eject channels for ejecting ink, a plurality of non-eject channels provided in both sides of the eject channels that do not eject ink, separation walls at least partly formed of polarized piezoelectric ceramic to isolate the eject channels from the non-eject channels, and electrodes formed on the separation walls to generate an ink driving field to the piezoelectric ceramic with application of a voltage thereto. The method includes dividing the electrodes in the non-eject channels by forming on a substrate having a piezoelectric ceramic layer first grooves that define the eject channels, second grooves, which are wider than the first grooves, to define the non-eject channels, and the separation walls; forming a conductive layer along all of the internal surfaces of the first and second grooves; and removing the conductive layers formed at the bottom surfaces of the second grooves.
According to a method of manufacturing an ink ejecting device of a fourth aspect of the present invention, the conductive layers formed at the bottom surfaces of the second grooves having the width wider than that of the first grooves can be removed by cutting thereof with a rotating disk tool, thereby dividing the electrodes in the non-eject channels.
According to a method of manufacturing an ink ejecting device of a fifth aspect of the present invention, the electrodes in the non-eject channels can be divided with good productivity by forming the first grooves and removing the conductive layers by using rotating disk tools having the same width.
As is apparent from above description, in the ink ejecting device of the first aspect, since the non-eject channel is wider than the eject channel, the electrodes in the non-eject channel can be divided reliably. Therefore, cost reduction can be realized, manufacturing yield can be improved and higher productivity can also be attained.
In the ink ejecting device of the second aspect, since the electrodes in the eject channels are grounded and the ink can be ejected by applying a voltage to the electrodes in the non-eject channels to deform the separation walls, an insulating film on the electrodes in the eject channels to be placed in contact with the ink is no longer required, achieving reduction of cost, improvement of manufacturing yield and excellent productivity.
In the ink ejecting device of the third aspect, since the second groove that defines the non-eject channel is formed wider than the first groove that defines the eject channel, the conductive layer at the bottom surface of the second groove can be accurately removed, achieving lower cost, improvement in manufacturing yield and good productivity.
In the method of manufacturing an ink ejecting device of the fourth aspect, since the conductive layer formed at the bottom surface of the second groove formed wider than the first groove can be removed by the cutting process using a rotating disk tool, the electrodes in the non-eject channel can be divided accurately.
In the method of manufacturing an ink ejecting device of the fifth aspect, the electrodes in the non-eject channel can be divided with good productivity by forming the first groove and removing the conductive layer through the cutting process using rotating disk tools having the same width.
These and other aspects and advantages of the invention will be described in or apparent from the following detailed description of preferred embodiments.